The incidence and mortality of thromboembolic events in lumbar spine surgery

Prone Position Increases the Risk of Postoperative Deep Vein Thrombosis in Cervical Spine Surgery by Limiting Venous Return in the Lower Limbs

STUDY DESIGN

A retrospective clinical study with confirmatory evaluation in healthy volunteers.

OBJECTIVE

To investigate the association between deep vein thrombosis (DVT) and surgical position after cervical spine surgery.

SUMMARY OF BACKGROUND DATA

It is unclear whether posterior cervical surgery using the prone position increases the risk of postoperative DVT relative to anterior cervical surgery.

MATERIALS AND METHODS

A total of 340 patients undergoing surgery for degenerative cervical myelopathy were included. Multivariate analysis was used to identify the predictors of postoperative DVT, adjusting for potential confounders. In addition, 45 healthy volunteers were used to study the blood flow velocity and intravascular diameter of the posterior tibial vein (PTV) and popliteal vein (PV) of the subjects, which were monitored by ultrasound and compared among three positions (supine, prone, and prone with iliac cushions).

RESULTS

Multivariate analysis showed that advanced age (above 63.5 yr old), preoperative varicose veins, D-dimer >0.255 mg/L, bleeding volume >303 mL, and prone positioning were significantly associated with DVT after cervical spine surgery. The results of vascular ultrasound showed that the blood flow velocities of the PV and PTV in the prone position with cushions were significantly lower than those in the supine position. The diameter of PV in the prone position with cushions was also significantly larger. The blood flow velocity and diameter of PV in the prone position with cushions were significantly lower and larger, respectively, than those in the prone position without cushions.

CONCLUSIONS

Posterior cervical surgery in the prone position was significantly associated with postoperative DVT. The prone position with iliac cushions may decrease venous flow within the lower extremities due to compression of the iliac veins, obstructing venous return and thus increasing the incidence of postoperative DVT. The prone position without iliac cushions may reduce the potential for DVT.

LEVEL OF EVIDENCE

3.

Predicting Complications in 153 Lumbar Pedicle Subtraction Osteotomies by a Single Surgeon Over a 6-Year Period

INTRODUCTION

Pedicle subtraction osteotomy (PSO) is a complex surgical procedure that provides correction of moderate sagittal imbalance. Surgical complications have adverse effects on patient outcomes and healthcare costs, making it imperative for clinical researchers to focus on minimizing complications. However, when it comes to risk modeling of PSO surgery, there is currently no consensus on which patient characteristics or measures should be used. This study aimed to describe complications and compare the performance of various sociodemographic characteristics, surgical variables, and established risk indices in predicting postoperative complications, infections, and readmissions after lumbar PSO surgeries.

METHODS

A review was conducted on 191 patients who underwent PSO surgery at a single institution by a single fellowship-trained orthopaedic spine surgeon between January 1, 2018, and December 31, 2021. Demographic, intraoperative, and postoperative data within 30 days, 1 year, and 2 years of the index procedure were evaluated. Descriptive statistics, t-test, chi-squared analysis, and logistic regression models were used.

RESULTS

Intraoperative complications were significantly associated with coronary artery disease (odds ratios [OR] 3.95, P = 0.03) and operating room time (OR 1.01, P = 0.006). 30-day complications were significantly cardiovascular disease (OR 2.68, P = 0.04) and levels fused (OR 1.10, P = 0.04). 2-year complications were significantly associated with cardiovascular disease (OR 2.85, P = 0.02). 30-day readmissions were significantly associated with sex (4.47, 0.04) and length of hospital stay (χ2 = 0.07, P = 0.04). 2-year readmissions were significantly associated with age (χ2 = 0.50, P = 0.03), hypertension (χ2 = 4.64, P = 0.03), revision surgeries (χ2 = 5.46, P = 0.02), and length of hospital stay (χ2 = 0.07, P = 0.03).

DISCUSSION

This study found that patients with coronary vascular disease and longer fusions were at higher risk of postoperative complications and patients with notable intraoperative blood loss were at higher risk of postoperative infections. In addition, physicians should closely follow patients with extended postoperative hospital stays, with advanced age, and undergoing revision surgery because these patients were more likely to be readmitted to the hospital.

Combined Use of Tranexamic Acid and Rivaroxaban in Posterior/Transforaminal Lumbar Interbody Fusion Surgeries Safely Reduces Blood Loss and Incidence of Thrombosis: Evidence From a Prospective, Randomized, Double-Blind, Placebo-Controlled Study

STUDY DESIGN

A prospective, randomized, double-blind, placebo-controlled study.

OBJECTIVES

There are few studies examining the balance between preventing venous thrombus embolism (VTE) and reducing blood loss in posterior/transforaminal lumbar interbody fusion (PLIF/TLIF) surgeries. This study aimed to evaluate the efficacy and safety of the combine application of TXA and rivaroxaban in patients undergoing PLIF/TLIF and explore relevant factors related to blood loss and VTE.

METHODS

Patients in group A which was the control group received 0.9% NaCl solution intravenously. Group B was treated by an intravenous injection of 2 g tranexamic acid (TXA) and the local use of 1 g intraoperatively. Group C was treated the same as group B intraoperatively, and they received 10 mg rivaroxaban qd treatment postoperatively. Eligible patients with an Autar score ≤ 10 were randomly assigned to group A or group B. Patients with an Autar score >10 were allocated into group C.

RESULTS

The intraoperative blood loss and postoperative drainage were lower in groups B and C than in group A (P < .001). The blood transfusion rate in group B was lower than that in group A (P < .001), while the incidence of VTE in group C was lower (P < .001). Four factors were found to be positively correlated with obvious total blood loss (P < .05). The data showed that 5 factors were correlated with the development of a thrombus (P < .1).

CONCLUSIONS

The combination of TXA and rivaroxaban in PLIF/TLIF patients is safe and effective in reducing D-dimer levels associated with VTE and reducing blood loss.

Venous Thromboembolism Rates Have Not Decreased in Elective Lumbar Fusion Surgery from 2011 to 2020

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

This study aimed to (1) evaluate for any temporal trends in the rates of VTE, deep venous thrombosis (DVT), pulmonary embolism (PE), and mortality from 2011 to 2020 and (2) identify the predictors of VTE following lumbar fusion surgery.

METHODS

Annual incidences of 30-day VTE, DVT, PE, and mortality were calculated for each of the operation year groups from 2011 to 2020. Multivariable Poisson regression was utilized to test the association between operation year and primary outcomes, as well as to identify significant predictors of VTE.

RESULTS

A total of 121,205 patients were included. There were no statistically significant differences in VTE, DVT, PE, or mortality rates among the operation year groups. Multivariable regression analysis revealed that compared to 2011, operation year 2019 was associated with significantly lower rates of DVT. Age, BMI, prolonged operation time, prolonged length of stay, non-home discharge, anterior fusion, smoking status, functional dependence, and chronic steroid use were identified as independent predictors of VTE following lumbar fusion. Female sex, Hispanic ethnicity, and outpatient surgery setting were identified as protective factors from VTE in this cohort.

CONCLUSIONS

Rates of VTE after lumbar fusion have remained mostly unchanged between 2011 and 2020. Older age, higher BMI, longer operation time, prolonged length of stay, non-home discharge, anterior fusion, smoking, functional dependence, and steroid use were independent predictors of VTE after lumbar fusion, while female sex, Hispanic ethnicity, and outpatient surgery were the protective factors.

A prospective marker for the prediction of postoperative deep venous thrombosis: Neutrophil extracellular traps

Deep venous thrombosis (DVT) is a common medical complication in patients with lumbar fractures. The current study aimed to investigate the predictive value of neutrophil extracellular traps (NETs) in postoperative DVT formation in patients with lumbar fractures and to develop a nomogram relating clinical admission information for prediction. Patients who underwent open reduction and pedicle screw internal fixation in the treatment of single-segment lumbar fracture in the Department of Spine Surgery, the First Affiliated Hospital of Nanjing Medical University, from December 2020 to June 2022 were enrolled in this study. Baseline data and laboratory results were collected from enrollees, and the primary study endpoint event was the occurrence of DVT in patients after surgery. Multivariable logistic regression analysis was used to identify risk factors associated with higher odds of DVT after surgery. A nomogram was constructed using the results of the multivariable model. The calibration plot and receiver operating characteristics (ROC) curve were used to show the satisfactory predictive capacity of the model. Of these 393 patients who did not have DVT preoperatively, 79 patients developed it postoperatively, and 314 did not, respectively. Multivariate analysis showed that higher body mass index (BMI) (BMI between 24 and 28: RR = 1.661, 95% CI = 0.891-3.094; BMI ≤28: RR = 5.625, 95% CI = 2.590-12.217; reference: BMI <24), neutrophils (RR = 1.157, 95% CI 1.042-1.285), D-dimer (RR = 1.098, 95% CI 1.000-1.206), and citrullinated histone H3 (CitH3) (RR = 1.043, 95% CI 1.026-1.060) were independent risk factors for postoperative DVT. Using the multivariable analysis, we then constructed a nomogram to predict DVT, which was found to have an area under the curve of 0.757 (95% CI = 0.693-0.820). Calibration plots also showed the satisfied discrimination and calibration of the nomogram. In conclusion, patients with lumbar fractures with postoperative DVT had higher levels of NETs in the circulation preoperatively compared to those without postoperative DVT. Furthermore, based on BMI, D-dimer, neutrophils, and CitH3, we developed a predictive model to predict postoperative DVT incidence in these patients.

Perioperative stroke in patients undergoing spinal surgery: a retrospective cohort study

BACKGROUND

The incidence of perioperative stroke following spinal surgery, including ischemic and hemorrhagic stroke, has not been fully investigated in the Chinese population. Whether specific spinal or emergency/elective procedures are associated with perioperative stroke remains controversial. This study aimed to investigate the incidence of perioperative stroke, health economic burden, clinical outcomes, and associated risk factors.

METHOD

A retrospective cohort study using an electronic hospital information system database was conducted from Jan 1, 2015, to Jan 1, 2021, in a tertiary hospital in China. Patients aged ≥18 years who had undergone spinal surgery were included in the study. We recorded patient demographics, comorbidities, and health economics data. Clinical outcomes included perioperative stroke during hospitalization and associated risk factors. The patients' operative data, anesthetic data, and clinical manifestations were recorded.

RESULT

A total of 17,408 patients who had undergone spinal surgery were included in this study. Twelve patients had perioperative stroke, including seven ischemic stroke (58.3%) and five hemorrhagic stroke (41.7%). The incidence of perioperative stroke was 0.07% (12/17,408). In total, 12 stroke patients underwent spinal fusion. Patients with perioperative stroke were associated with longer hospital stay (38.33 days vs. 9.78 days, p < 0.001) and higher hospital expenses (RMB 175,642 vs. RMB 81,114, p < 0.001). On discharge, 50% of perioperative patients had severe outcomes. The average onset time of perioperative stroke was 1.3 days after surgery. Stroke history (OR 146.046, 95% CI: 28.102-759.006, p < 0.001) and hyperlipidemia (OR 4.490, 95% CI: 1.182-17.060, p = 0.027) were associated with perioperative stroke.

CONCLUSION

The incidence of perioperative stroke of spinal surgery in a tertiary hospital in China was 0.07%, with a high proportion of hemorrhagic stroke. Perioperative stroke patients experienced a heavy financial burden and severe outcomes. A previous stroke history and hyperlipidemia were associated with perioperative stroke.

Underweight patients are the highest risk body mass index group for perioperative adverse events following stand-alone anterior lumbar interbody fusion

BACKGROUND CONTEXT

Prior studies investigating the association between Body Mass Index (BMI) and patient outcomes following spine surgery have had inconsistent conclusions, likely owing to insufficient power, confounding variables, and varying definitions and cutoffs for BMI categories (eg, underweight, overweight, obese, etc.). Further, few studies have considered outcomes among low BMI cohorts.

PURPOSE

The current study analyzes how anterior lumbar interbody fusion (ALIF) perioperative outcomes vary along the BMI spectrum, using World Health Organization (WHO) categories of BMI.

STUDY DESIGN/SETTING

A retrospective cohort study.

PATIENT SAMPLE

Patients undergoing stand-alone one or two-level anterior lumbar interbody fusion (ALIF) found in the 2005-2018 American College of Surgeons National Surgical Quality Improvement Program (NSQIP) databases.

OUTCOME MEASURES

Thirty-day adverse events, hospital readmissions, post-operative infections, and mortality.

METHODS

Stand-alone one or two-level ALIF surgical cases were identified and extracted from the 2005-2018 National Surgical Quality Improvement Program (NSQIP) database. Posterior cases and those primary diagnoses of trauma, tumor, infection, or emergency presentation were excluded. Patients were then binned into WHO guidelines of BMI. The incidence of adverse outcomes within 30-day post-operation was defined. Odds ratios of adverse outcomes, normalized to the average risk of normal-weight subjects (BMI 18.5-24.9 kg/m³), were calculated. Multivariate analysis was then performed controlling for patient factors.

RESULTS

In total, 13,710 ALIF patients were included in the study. Incidence of adverse events was elevated in both the underweight (BMI<18.5 kg/m³) and super morbidly obese (>50 kg/m³), however, multivariate risks for adverse events and postoperative infection were elevated for underweight patients beyond those found in any other BMI category. No effect was noted in these identical variables between normal, overweight, obese class 1, or even obese class 2 patients. Multivariate analysis also found overweight patients to show a slightly protective trend against mortality while the super morbidly obese had elevated odds.

CONCLUSIONS

Underweight patients are at greater odds of experiencing postoperative adverse events than normal, overweight, obese class 1, or even obese class 2 patients. The present study identifies underweight patients as an at-risk population that should be given additional consideration by health systems and physicians, as is already done for those on the other side of the BMI spectrum.

Retrospective Data Analysis for Enhanced Recovery After Surgery (ERAS) Protocol for Elderly Patients with Long-Level Lumbar Fusion

BACKGROUND

Enhanced recovery after surgery (ERAS) for spinal surgery is new; specifically, an ERAS program for elderly patients is lacking. Geriatric patients have special characteristics that result in further harm by surgical stress. ERAS interventions are designed to improve recovery after surgery and can result in substantial benefits in clinical outcomes and cost-effectiveness. We aimed to determine whether ERAS significantly improved satisfaction and outcomes in elderly patients with long-level lumbar fusion.

METHODS

Patients >70 years old with lumbar disc herniation or lumbar spinal stenosis who underwent lumbar fusion of ≥3 levels from July 2019 to June 2021 (ERAS group) and from January 2018 to June 2019 (non-ERAS group) were enrolled. Demographic, comorbidity, and surgical data were collected from electronic medical records. ERAS interventions were categorized as preoperative, intraoperative, and postoperative. We also evaluated primary outcome, surgical complications, and length of stay (LOS).

RESULTS

The study included 154 patients, 72 in the ERAS group and 82 case-matched patients in the non-ERAS group. Overall, ERAS pathway compliance was 91%. There were no significant differences in readmission and mortality rates at 30-day follow-up between the ERAS and non-ERAS groups. Statistically significant decreases were observed in the ERAS group in complications (6 in ERAS group vs. 19 in non-ERAS group, P = 0.013) and LOS (17.74 ± 5.56 days in ERAS group vs. 22.13 ± 12.21 days in non-ERAS group, P = 0.041). Multivariable linear regression showed that implementation of ERAS (P = 0.002) was correlated with LOS. Multivariable logistic regression showed that implementation of ERAS (P = 0.004) was correlated with complications.

CONCLUSIONS

The ERAS protocol used in elderly patients after long-level lumbar fusion surgery was safe and associated with incremental benefits regarding complications and LOS.

Narrative Review of Antiplatelet and Anticoagulant Medications for Venous Thromboembolism Prevention in Spine Surgery

STUDY DESIGN

This was a narrative review.

OBJECTIVE

The objective of this study was to identify commonly utilized venous thromboembolism (VTE) prophylactic measures, spine surgeon perspective, and provide pharmacologic recommendations from the literature.

SUMMARY OF BACKGROUND DATA

Considered a preventable cause of morbidity and mortality, VTE remains an important iatrogenic diagnosis of concern. Reported rates of VTE following spine surgery vary widely (0.3%-31.0%).

MATERIALS AND METHODS

A MEDLINE query identified literature reporting on VTE prevention and outcomes in the setting of spine surgery. Findings extracted from the included articles were summarized in a narrative review format to identify salient aspects of the current literature.

RESULTS

Sixty articles were summarized. Many anticoagulation medications that are described in the literature target factors involved in the coagulation cascade common pathway including aspirin and other antiplatelet medications, heparins, and warfarin. Newer direct inhibitors of thrombin and factor Xa are now being utilized for VTE prevention, although with limited use specifically in spine surgery.

CONCLUSIONS

Perioperative management of antiplatelet and anticoagulation medications in spine surgery requires evidence-based protocols that can account for patient comorbidities and surgery-specific features. Future studies should prospectively focus on establishing stronger recommendations based on pathology, surgical indications, patient comorbidities, region of the spine, and broad surgical intervention to enable effective prophylaxis for VTE.

LEVEL OF EVIDENCE

Level II.

Postoperative Epidural Hematoma

Symptomatic postoperative epidural hematomas are rare, with an incidence of 0.10% to 0.69%. Risk factors have varied in the literature, but multiple studies have reported advanced age, preoperative or postoperative coagulopathy, and multilevel laminectomy as risk factors for hematoma. The role of pharmacologic anticoagulation after spine surgery remains unclear, but multiple studies suggest it can be done safely with a low risk of epidural hematoma. Prophylactic suction drains have not been found to lower hematoma incidence. Most symptomatic postoperative epidural hematomas present within the first 24 to 48 hours after surgery but can present later. Diagnosis of a symptomatic hematoma requires correlation of clinical signs and symptoms with a compressive hematoma on MRI. Patients will usually first complain of a marked increase in axial pain, followed by radicular symptoms in the extremities, followed by motor weakness and sphincter dysfunction. An MRI should be obtained emergently, and if it confirms a compressive hematoma, surgical evacuation should be carried out as quickly as possible. The prognosis for neurologic improvement after evacuation depends on the time delay and the degree of neurologic impairment before evacuation.

The risks and benefits of early venous thromboembolism prophylaxis after elective spinal surgery: A single-centre experience

BACKGROUND

There is a wide ranging incidence of venous thromboembolism after surgery and it continues to be a major cause of morbidity after spinal procedures.This study's aim was to investigate the relationship between timing and administration of venous thromboembolism (VTE) pharmacologic chemoprophylaxis after spinal surgery and the resulting VTE and bleeding complications by reviewing current practices and outcomes at a high-volume single institution to better define opportunities for perioperative intervention to prevent VTE without increasing bleeding complications.

METHODS

All patients who underwent elective one or two-stage lumbar spinal fusion procedures were identified. A logistic regression was used to evaluate (1) risk of symptomatic VTE within 30 days of surgery and (2) bleeding-related complications. The odds of developing a VTE as well as bleeding-related complications were compared among the three treatment groups: no chemoprophylaxis, chemoprophylaxis < 24h of surgery and chemoprophylaxis given > 24h post-surgery.

RESULTS

When adjusted for doses administered, the odds of developing a postoperative VTE within 30 days were 0.189 (95% confidence interval (0.044, 0.808)) in patients who received anticoagulation < 24h postoperatively, compared to those who received no anticoagulation (p = 0.025). There was no difference in bleeding rates.

CONCLUSION

Patients undergoing elective spinal surgery who received anticoagulation within 24h of the conclusion of their procedure had an 81% reduction in the odds of developing a deep vein thrombosis within 30 days with no significant difference in bleeding complications.

Consensus statement for perioperative care in lumbar spinal fusion: Enhanced Recovery After Surgery (ERAS®) Society recommendations

BACKGROUND

Enhanced Recovery After Surgery (ERAS) evidence-based protocols for perioperative care have led to improvements in outcomes in numerous surgical areas, through multimodal optimization of patient pathway, reduction of complications, improved patient experience and reduction in the length of stay. ERAS represent a relatively new paradigm in spine surgery.

PURPOSE

This multidisciplinary consensus review summarizes the literature and proposes recommendations for the perioperative care of patients undergoing lumbar fusion surgery with an ERAS program.

STUDY DESIGN

This is a review article.

METHODS

Under the impetus of the ERAS® society, a multidisciplinary guideline development group was constituted by bringing together international experts involved in the practice of ERAS and spine surgery. This group identified 22 ERAS items for lumbar fusion. A systematic search in the English language was performed in MEDLINE, Embase, and Cochrane Central Register of Controlled Trials. Systematic reviews, randomized controlled trials, and cohort studies were included, and the evidence was graded according to the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system. Consensus recommendation was reached by the group after a critical appraisal of the literature.

RESULTS

Two hundred fifty-six articles were included to develop the consensus statements for 22 ERAS items; one ERAS item (prehabilitation) was excluded from the final summary due to very poor quality and conflicting evidence in lumbar spinal fusion. From these remaining 21 ERAS items, 28 recommendations were included. All recommendations on ERAS protocol items are based on the best available evidence. These included nine preoperative, eleven intraoperative, and six postoperative recommendations. They span topics from preoperative patient education and nutritional evaluation, intraoperative anesthetic and surgical techniques, and postoperative multimodal analgesic strategies. The level of evidence for the use of each recommendation is presented.

CONCLUSION

Based on the best evidence available for each ERAS item within the multidisciplinary perioperative care pathways, the ERAS® Society presents this comprehensive consensus review for perioperative care in lumbar fusion.

Is There Value in Venous Thromboembolism Chemoprophylaxis After Pediatric Scoliosis Surgery? A 28-Year Single Center Study

BACKGROUND

With a recognized increase in the incidence of venous thromboembolism (VTE) in children, especially in those with complex, chronic conditions, it is important for patient safety and risk management to identify subgroups that would benefit from prophylactic treatment. The aim of our study was to assess whether scoliosis surgery in children was associated with an increased incidence of VTE, including deep venous thrombosis (DVT) and pulmonary embolism, and if chemoprophylaxis is warranted.

METHODS

We reviewed our institution's Pediatric Orthopaedic Spine Database (1992-2019) to identify patients who had a symptomatic VTE postoperatively.

RESULTS

There were 1471 patients (1035 female, 436 male) with a mean age at surgery of 12.1±3.2 years (range, 1 to 18 y) underwent posterior spinal fusion and instrumentation (2131 procedures). No patients were given pharmacological VTE prophylaxis, and no routine screening for VTE was performed. Two patients had a lower extremity DVT (0.13%) within 6 months following surgery, (range, 55 to 161 d). Neither patient had a subsequent pulmonary embolism. They were 9 and 17 years of age with a diagnosis of neuromuscular scoliosis (1 each postpolio and myelodysplasia). One affected patient had a central venous line inserted perioperatively, a known risk factor for thromboembolism. All DVTs were treated with appropriately dosed anticoagulants. None had a family history of hypercoagulation.

CONCLUSIONS

The risk of symptomatic VTE is extraordinarily low after pediatric spinal deformity surgery. Mechanical prophylaxis is sufficient in most cases. Further multi-center studies may help identify patient specific risk factors.

[Expert consensus on the implementation of enhanced recovery after surgery in percutaneous endoscopic interlaminar lumbar decompression/discectomy (2020)]

In recent years, enhanced recovery after surgery (ERAS) has been widely used in spine surgery and achieved satisfactory results. In order to standardize the ERAS implementation process and application in percutaneous endoscopic interlaminar lumbar decompression/discectomy (PEID), we reviewed the literatures and cited evidence-based medicine data, and had a national comprehensive discussion among experts of the Group of Minimally Invasive Spinal Surgery and Enhanced Recovery, Professional Committee of Orthopedic Surgery and Enhanced Recovery, Association of China Rehabilitation Technology Transformation and Promotion. Altogether, the up-to-date expert consensus have been achieved. The consensus may provide the reference for clinical treatment in aspect of the standardization of surgical operations, the reduction of surgical trauma and complications, the optimization of perioperative pain and sleep management, the prevention of venous thrombosis, and the guidance of patients' functional training and perioperative education.

An Evidence-Based Algorithm for Determining Venous Thromboembolism Prophylaxis After Degenerative Spinal Surgery

BACKGROUND

Although venous thromboembolism (VTE) is a potentially serious and life-threatening complication, there is no widely accepted protocol to guide VTE prophylaxis in adult degenerative spinal surgery, and pharmacologic overtreatment may result in hemorrhagic complications. Previously, we published the VTE Prophylaxis Risk/Benefit Score, an evidence-based algorithm that balances the risk and consequences of thrombotic versus hemorrhagic complications by taking consideration of patient-related risks, procedure-related risks, and the risk of neurological compromise to guide VTE prophylaxis. To objective of this study was to validate the VTE Prophylaxis Risk/Benefit Score.

METHODS

From January 1, 2016, to December 31, 2017, VTE Prophylaxis Risk/Benefit Scores and corresponding prophylaxes were prospectively assigned. When indicated, chemoprophylaxis was dosed 24 to 36 hours postoperatively to allow for adequate surgical hemostasis. Patients were retrospectively evaluated for immediate and short-term complications. The Fisher exact test compared incidence of complications by VTE prophylaxis. Multinomial logistic regression modeled the probability of complication by prophylaxis type, demographics, and comorbidities. Significance was set at P < .05.

RESULTS

Of the 266 patients who met inclusion criteria, 79.3% were given mechanical prophylaxis alone and 20.7% were given combined mechanical and chemical prophylaxis. Complications including VTE (0.38%), delayed wound healing or infection (2.26%), and hematoma (0.75%) were observed at rates similar to or lower than previously published studies with increased utilization of chemoprophylaxis. Use of chemoprophylaxis and continuation of perioperative aspirin were significantly associated with the development of a hemorrhagic complication. No patient developed persistent neurologic deficit from hematoma or pulmonary embolism.

CONCLUSIONS

The VTE Prophylaxis Risk/Benefit Score comprehensively considers the risk of thrombotic, wound, and bleeding complications and is an effective tool for determining appropriate thromboprophylaxis in adult degenerative spinal surgery.

LEVEL OF EVIDENCE

3.

Cost- Effectiveness of Avatrombopag for the Treatment of Thrombocytopenia in Patients with Chronic Liver Disease

Background and Aim

Thrombocytopenia is common in people with chronic liver disease, who frequently undergo invasive procedures. To minimize the risk of bleeding, prophylactic platelet transfusions have traditionally been used but carry many risks. The aim of this study was to evaluate the cost-effectiveness of avatrombopag compared with platelet transfusion and lusutrombopag as a treatment for thrombocytopenia in adult patients with chronic liver disease scheduled to undergo a medical procedure.

Methods

A decision-tree model was developed from a US payer perspective to capture acute events observed in phase 3 global randomized controlled clinical trials and, to support exploratory analyses, potential longer-term complications resulting from a major bleed or thromboembolic event. Treatment costs were taken from publicly available data sources. The interventions were evaluated in the overall trial populations and in subpopulations with higher and lower baseline platelet counts. Results were presented as incremental cost per platelet transfusion avoided. One-way and probabilistic sensitivity analyses were conducted.

Results

In the overall population, avatrombopag reduced the need for platelet transfusions and produced cost-savings compared with platelet transfusion (80% fewer prophylactic platelet transfusions, $4250 lower costs) and lusutrombopag (42% fewer prophylactic platelet transfusions, $5819 lower costs). Similar results were seen in both the higher and lower platelet count subpopulations. The one-way and probabilistic sensitivity analyses found that the use of avatrombopag is cost-saving with the incremental cost-effectiveness ratio in quadrant IV (decreased costs, prophylactic platelet transfusions avoided).

Conclusion

The use of avatrombopag is expected to be cost-saving while reducing the need for prophylactic platelet transfusions compared with platelet transfusion and lusutrombopag.

Perioperative Anticoagulation Management in Spine Surgery: Initial Findings From the AO Spine Anticoagulation Global Survey

STUDY DESIGN

Cross-sectional, international survey.

OBJECTIVES

This study addressed the global perspectives concerning perioperative use of pharmacologic thromboprophylaxis during spine surgery along with its risks and benefits.

METHODS

A questionnaire was designed and implemented by expert members in the AO Spine community. The survey was distributed to AO Spine's spine surgeon members (N = 3805). Data included surgeon demographic information, type and region of practice, anticoagulation principles, different patient scenarios, and comorbidities.

RESULTS

A total of 316 (8.3% response rate) spine surgeons completed the survey, representing 64 different countries. Completed surveys were primarily from Europe (31.7%), South/Latin America (19.9%), and Asia (18.4%). Surgeons tended to be 35 to 44 years old (42.1%), fellowship-trained (74.7%), and orthopedic surgeons (65.5%) from academic institutions (39.6%). Most surgeons (70.3%) used routine anticoagulation risk stratification, irrespective of geographic location. However, significant differences were seen between continents with anticoagulation initiation and cessation methodology. Specifically, the length of a procedure (P = .036) and patient body mass index (P = .008) were perceived differently when deciding to begin anticoagulation, while the importance of medical clearance (P < .001) and reference to literature (P = .035) differed during cessation. For specific techniques, most providers noted use of mobilization, low-molecular-weight heparin, and mechanical prophylaxis beginning on postoperative 0 to 1 days. Conversely, bridging regimens were bimodal in distribution, with providers electing anticoagulant initiation on postoperative 0 to 1 days or days 5-6.

CONCLUSION

This survey highlights the heterogeneity of spine care and accentuates geographical variations. Furthermore, it identifies the difficulty in providing consistent perioperative anticoagulation recommendations to patients, as there remains no widely accepted, definitive literature of evidence or guidelines.

Intraoperative Fluid Management in Patients Undergoing Spine Surgery: A Narrative Review

Fluid management has been widely recognized as an important component of the perioperative care in patients undergoing major procedures including spine surgeries. Patient- and surgery-related factors such as age, length of the surgery, massive intraoperative blood loss, and prone positioning, may impact the intraoperative administration of fluids. In addition, the type of fluid administered may also affect post-operative outcomes. Published literature describing intraoperative fluid management in patients undergoing major spine surgeries is limited and remains controversial. Therefore, we reviewed current literature on intraoperative fluid management and its association with post-operative complications in spine surgery.

Decompression With or Without Fusion for Lumbar Stenosis: A Cost Minimization Analysis

STUDY DESIGN

Retrospective database review.

OBJECTIVE

Compare 1-year episode of care costs between single-level decompression and decompression plus fusion for lumbar stenosis.

SUMMARY OF BACKGROUND DATA

Lumbar stenosis is the most common indication for surgery in patients over 65. Medicare direct hospital costs for lumbar surgery reached $1.65 billion in 2007. Despite stenosis being a common indication for surgery, there is debate as to the preferred surgical treatment. Cost-minimization analysis is a framework that identifies potential cost savings between treatment options that have similar outcomes. We performed a cost-minimization analysis of decompression versus decompression with fusion for lumbar stenosis from the payer perspective.

METHODS

An administrative claims database of privately insured patients (Humana) identified patients who underwent decompression (n = 5349) or decompression with fusion (n = 8540) for lumbar stenosis with and without spondylolisthesis and compared overall costs. All patients were identified and costs identified for a 1-year period. Complication rates and costs were described using summary statistics.

RESULTS

Mean treatment costs at 1 year after surgery were higher for patients who underwent decompression and fusion compared to patients who underwent decompression alone ($20,892 for fusion vs. $6329 for decompression; P < 0.001). Facility costs (P < 0.001), surgeon costs (P < 0.001), and physical therapy costs (P < 0.001) were higher in the fusion group. Cost differences related to infection or durotomy reached significance (P < 0.04). No difference in cost was identified for supplies.

CONCLUSION

Decompression had significantly lower costs for the treatment of lumbar stenosis, including treatment for postoperative complications. If cost minimization is the primary goal, decompression is favored for surgical treatment of lumbar stenosis. Other factors including shared decision-making directed toward patient's values, patient-reported outcomes, and preferences should also be recognized as drivers of healthcare decisions.

LEVEL OF EVIDENCE

3.

The True Effect of a Lumbar Dural Tear on Complications and Cost

STUDY DESIGN

Retrospective database analysis.

OBJECTIVE

The aim of this study was to match risk factors for complications in patients who did and did not sustain a dural tear while undergoing posterior lumbar spine surgery and compare local and systemic complications.

SUMMARY OF BACKGROUND DATA

Current data do not adequately define whether the event of sustaining an isolated dural tear increases the risk for postoperative complications while controlling for other confounding risk factors.

METHODS

The PearlDiver Database was queried for patients who underwent posterior lumbar spine decompression and/or fusion for degenerative pathology. Patients with and without dural tears were 1:2 matched based on demographic variables and comorbidities. Complications, cost, length of stay (LOS), and readmission rates were analyzed.

RESULTS

The 1:2 matched cohort included 9038 patients with a dural tear and 17,340 patients without a dural tear. All complications assessed were significantly higher in the dural tear group (P < 0.03). Venothromboembolic (VTE) events occurred in 1.3% of patients with a dural tear and 0.9% of patients without a dural tear (odds ratio [OR] 1.46, P < 0.0001). Meningitis occurred in 25 patients (0.3%) with a dural tear and eight patients (<0.1%) without a dural tear (OR 6.0, P < 0.0001). Patients with a dural tear had 120% higher medical costs, 200% greater LOS, and were two times more likely to be readmitted (P < 0.0001).

CONCLUSION

Sustaining a dural tear while undergoing posterior lumbar spinal decompression and/or fusion for degenerative pathology significantly increased the risk of complications and increased length of stay, risk of readmission, and overall 90-day hospital cost. Dural tears specifically increased the risk of a VTE complication by 1.46 times and meningitis by six times; these are important complications to have a high degree of suspicion for in the setting of durotomy, as they can lead to significant morbidity for the patient.

LEVEL OF EVIDENCE

3.

Outcomes Following Posterior Lumbar Fusion in Patients with Polycythemia Vera

BACKGROUND

Polycythemia vera (PV) is a chronic myeloproliferative neoplasm that is associated with increased risk for venous and arterial thromboembolism. The aim of this study was to evaluate outcomes following elective posterior lumbar fusion (PLF) and/or posterior interbody fusion (PLIF) among patients with PV.

METHODS

Using PearlDiver retrospective national database, Medicare patients <85 years old who underwent elective primary PLF (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] code 81.07) and/or PLIF (ICD-9-CM code 81.08) for degenerative lumbar spine pathologies during 2006-2013 were identified. Patients included in the PLF and/or PLIF cohort were separated into patients with a prior diagnosis of PV (ICD-9-CM code 238.4) and a control cohort of patients without PV. Comparisons of postoperative outcomes were made between the PV patient group and matched control group. Significance was set at 0.05.

RESULTS

Selected study participants included 1491 patients with PV and 29,056 patients in the matched control group. Patients with PV had a significantly increased rate of 90-day acute pulmonary embolism (1.9% vs. 1.2%, odds ratio [OR] 1.65, 95% confidence interval [CI] 1.10-2.38, P = 0.010), 90-day lower extremity deep vein thrombosis (3.4% vs. 1.9%, OR 1.81, 95% CI 1.33-2.40, P < 0.001), and 1-year diagnosis of surgical site infection (5.4% vs. 4.2%, OR 1.30, 95% CI 1.02-1.63, P = 0.027) compared with patients without PV. Nonetheless, PV was not associated with other major medical complications, including stroke, myocardial infarction, and mortality, following PLF and/or PLIF.

CONCLUSIONS

Patients with PV undergoing elective PLF and/or PLIF have a significantly increased risk for pulmonary embolism, lower extremity deep vein thrombosis, and surgical site infection.

Time-to-event analyses of lower-limb venous thromboembolism in aged patients undergoing lumbar spine surgery: a retrospective study of 1620 patients

After spine surgery, venous thromboembolism (VTE) is not uncommon in aged patients. This study investigates time-to-event risk factors of postoperative VTE based on medical records of aged patients (age≥60 yr) between January 2013 and December 2018. All participants had undergone lower extremity ultrasonography pre- and postoperatively at the first, second, fourth, eighth, and twelfth weeks. Mann-Whitney U tests and chi-square tests were used for univariate analyses, and Cox regression was utilized for multivariate analyses. A total of 1620 cases were recruited, VTE group (N=382, 23.6%) and non-VTE group (N=1238, 76.4%), aged 67 (IQR 11) years and 65 (IQR 6) years, respectively. The univariate analyses indicated significant differences between the VTE and non-VTE groups regarding advanced age, VTE history, hypertension, fusion, hospital stay, FIB, HDL, D-dimer, and TC (all P<0.05). The Cox regression showed that advanced age (OR=1.108; 95% CI, 1.091–1.126), VTE history (OR=4.962; 95% CI, 3.849–6.397), and hypertension (OR=1.344; 95% CI, 1.084–1.667) were the risk factors for postoperative VTE (P<0.05). The time-to-event analyses indicated that the hazard of VTE formation was highest in the first postoperative week. In conclusion, advanced age, VTE history, and hypertension are main risks for VTE formation, particularly in the first postoperative week.

Multimodal Nutritional Management in Primary Lumbar Spine Surgery: A Randomized Controlled Trial

STUDY DESIGN

A prospective randomized controlled trial.

OBJECTIVE

The purpose of this study was to evaluate the clinical effect and safety of a new multimodal nutritional management (MNM) protocol for patients receiving primary lumbar spine surgery.

SUMMARY OF BACKGROUND DATA

Poor nutritional status is common in the perioperative period in primary lumbar spine surgery, and may impede recovery after surgery.

METHODS

A total of 187 patients were included in this prospective randomized controlled trial. They were randomly assigned to the MNM group or the control group. Albumin (ALB) infusion, postoperative ALB level, electrolyte disorders, postoperative electrolyte levels, transfusion rate, postoperative hemoglobin level, length of stay (LOS), and complications were compared between the groups.

RESULTS

Compared with the control group, the rate and the total amount of ALB infusion were lower in the MNM group, and the postoperative level of ALB in the MNM group was higher on the first postoperative day, and the third postoperative day. The incidence of hypokalemia, hyponatremia, and hypocalcemia were lower in the MNM group. In the MNM group, the postoperative levels of sodium, potassium, and calcium were higher than the control group. The transfusion rate was similar between the two groups. The hemoglobin level was similar between the two groups on first postoperative day, but was higher in the MNM group on third postoperative day. LOS in the MNM group was shorter than in the control group. The incidence of wound drainage was lower in the MNM group. No statistical differences were observed regarding surgical complications between the two groups.

CONCLUSION

The MNM protocol effectively reduced ALB infusion, the incidence of electrolyte disorders, and wound drainage, increased the postoperative levels of ALB, sodium, potassium, and calcium, and reduced the LOS without increasing the rate of postoperative complications.

LEVEL OF EVIDENCE

2.

Risk Factors for Postoperative Venous Thromboembolic Events in Patients Undergoing Lumbar Spine Surgery

STUDY DESIGN

Retrospective, database study.

OBJECTIVES

The aim of this study was to investigate incidence and risk factors associated with venous thromboembolic events (VTEs) after lumbar spine surgery.

METHODS

Patients who underwent lumbar surgery between 2007 and 2014 were identified using the Humana within PearlDiver database. ICD-9 (International Classification of Diseases Ninth Revision) diagnosis codes were used to search for the incidence of VTEs among surgery types, patient demographics and comorbidities. Complications including DVT and PE were queried each day from the day of surgery to postoperative day 7 and for periods 0 to 1 week, 0 to 1 month, 0 to 2 months, and 0 to 3 months postoperatively.

RESULTS

A total of 64 892 patients within the Humana insurance database received lumbar surgery between 2007 and 2014. Overall VTE rate was 0.9% at 1 week, 1.8% at 1 month, and 2.6% at 3 months postoperatively. Among patients that developed a VTE within 1 week postoperatively, 45.3% had a VTE on the day of surgery. Patients with 1 or more identified risk factors had a VTE incidence of 2.73%, compared with 0.95% for patients without risk factors (P < .001). Risk factors associated with the highest VTE incidence and odds ratios (ORs) were primary coagulation disorder (10.01%, OR 4.33), extremity paralysis (7.49%, OR 2.96), central venous line (6.70%, OR 2.87), and varicose veins (6.51%, OR 2.58).

CONCLUSIONS

This study identified several patient comorbidities that were independent predictors of postoperative VTE occurrence after lumbar surgery. Clinical VTE risk assessment may improve with increased focus toward patient comorbidities rather than surgery type or patient demographics.

Incidence and Risk Factors for Venous Thromboembolism After Spine Surgery in Korean Patients

BACKGROUND

Data regarding the incidence of venous thromboembolism (VTE) after spine surgery are scarce. Identifying ideal candidates for pharmacologic thromboprophylaxis and balancing the risk of thromboembolic complications against the risk of permanent neurologic deficits from a spinal epidural hematoma (SEH) are difficult. Even guidelines cannot suggest the standard of thromboprophylaxis.

OBJECTIVES

This study aimed to identify the incidence of and risk factors for VTE after spine surgery in the Korean population. In addition, the rate of pharmacoprophylaxis and the incidence of SEH after spine surgery were analyzed.

METHODS

The study cohort was generated by extracting patients with disease codes of spine surgery and VTE from the Health Insurance Review & Assessment Service National Inpatient Sample in 2014. After analyzing the incidence of VTE after spine surgery, a univariate comparison was performed to examine the possible relationship between the incidence of VTE and the independent variable. Variables found to be significant were included in a multivariable analysis model for further analysis.

RESULTS

The incidence of VTE was 2.09% among all 21,261 patients who had spine surgery, and prophylaxis was applied to 7.89% of all patients who had spine surgery. Comorbidities and surgery-related risk factors were venous disease, cancer, respiratory disease, prolonged surgery hours, and increased total blood loss. Hospital-related risk factors were the location and hospital size.

CONCLUSIONS

On the basis of the incidence of VTE and the risk factors, more active prophylaxis is suggested for patients in the Korean population who undergo spine surgery.

Development and implementation of a comprehensive spine surgery enhanced recovery after surgery protocol: the Cleveland Clinic experience

Enhanced recovery after surgery (ERAS) protocols have been shown to be effective at reducing perioperative morbidity and costs while improving outcomes. To date, spine surgery protocols have been limited in scope, focusing only on specific types of procedures or specific parts of the surgical episode. The authors describe the creation and implementation of one of the first comprehensive ERAS protocols for spine surgery. The protocol is unique in that it has a comprehensive perioperative paradigm encompassing the entire surgical period that is tailored based on the complexity of each individual spine patient.

Rates of Mortality in Lumbar Spine Surgery and Factors Associated With Its Occurrence Over a 10-Year Period: A Study of 803,949 Patients in the Nationwide Inpatient Sample

Background

The rate of mortality in surgical procedures involving the lumbar spine has historically been low, and as a result, there has been difficulty providing accurate quantitative mortality rates to patients in the preoperative planning phase. Awareness of these mortality rates is essential in reducing postoperative complications and improving outcomes. Additionally, mortality rates can be influenced by procedure type and patient profile, including demographics and comorbidities. The purpose of this study is to assess rates and risk factors associated with mortality in surgical procedures involving the lumbar spine using a large national database.

Methods

The Nationwide Inpatient Sample database was reviewed from 2003 to 2012. A total of 803,949 patients age 18 years or older were identified by ICD-9CM procedure codes for spinal fusion or decompression of the lumbar spine. Mortality was stratified based on type of procedure (simple or complex fusion, decompression), patient demographics and comorbidities, and in-hospital complications. Binary logistic regression was used to identify the risk of death while controlling for comorbidities, race, sex, and procedure performed. Significance was defined as P < .05 differences relative to the overall cohort.

Results

Mortality for all patients requiring surgery of the lumbar spine was 0.13%. Mortality based on procedure type was 0.105% for simple fusions, 0.321% for complex fusions, and 0.081% for decompression only. Increased mortality was observed demographically in patients who were male (odds ratio [OR]: 1.75; 95% confidence interval [CI]: 1.51-2.03), black (OR: 1.40; CI: 1.10-1.79), ages 65-74 (OR: 1.46; CI: 1.25-1.70), and age 75+ (OR: 2.70; CI: 2.30-3.17). Comorbidities associated with the greatest increase in mortality were mild (OR: 10.04; CI: 7.76-13.01) and severe (OR: 26.47; CI: 16.03-43.70) liver disease and congestive heart failure (OR: 4.57; CI: 3.77-5.53). The complications with the highest mortality rates were shock (OR: 20.67; CI: 13.89-30.56) and pulmonary embolism (OR: 20.15; CI: 14.01-29.00).

Conclusions

From 2003 to 2012, the overall mortality rate in 803,949 lumbar spine surgery patients was 0.13%. Risk factors that were significantly associated with increased mortality rates were male gender, black race, and ages 65-74 and 75+. Comorbidities associated with an increased mortality rate were mild and severe liver disease and congestive heart failure. Inpatient complications with the highest mortality rates were shock and pulmonary embolism. These findings can be helpful to surgeons providing preoperative counseling for patients considering elective lumbar procedures and for allocating resources to treat and prevent perioperative complications leading to mortality.

Level of Evidence

3.

Risk factors and pharmacologic prophylaxis for venous thromboembolism in elective spine surgery

BACKGROUND CONTEXT

Venous thromboembolism (VTE) is a known complication after spine surgery, but prophylaxis guidelines are ambiguous for patients undergoing elective spine surgery.

PURPOSE

The objective of this study was to characterize the incidence and risk factors for VTE and the association of pharmacologic prophylaxis with VTE and bleeding complications after elective spine surgery.

STUDY DESIGN/SETTING

This is a retrospective cohort study of patients undergoing elective spine surgery in the National Surgical Quality Improvement Program (NSQIP) database and a retrospective cohort analysis at an academic medical center.

PATIENT SAMPLE

This study included 109,609 patients in the NSQIP database from 2005 to 2014 and 2,855 patients at the authors' institution from January 2013 to March 2016 who underwent elective spine surgery.

OUTCOME MEASURES

The incidence and risk factors for VTE were assessed in both cohorts based on the NSQIP criteria. The incidence of bleeding complications requiring reoperation was assessed based on operative reports in the institutional cohort.

MATERIALS AND METHODS

Associations of patient and procedure factors with VTE were characterized in the NSQIP population. In the single-institution cohort, in addition to NSQIP variables, a chart review was completed to determine the use of VTE prophylaxis, the history of prior VTE, and the incidence of hematoma requiring reoperation. The association of patient and procedure variables, including pharmacologic prophylaxis and history of prior VTE, with VTE and hematoma requiring reoperation were determined with multivariate regression.

RESULTS

Among 109,609 elective spine surgery patients in NSQIP, independent risk factors for VTE were greater age, male gender, increasing body mass index, dependent functional status, lumbar spine surgery, longer operative time, perioperative blood transfusion, longer length of stay, and other postoperative complications. There were 2,855 patients included in the institutional cohort. Pharmacologic prophylaxis was performed in 56.3% of the institutional patients, of whom 97.1% received unfractionated heparin. When controlling for patient and procedural variables, pharmacologic prophylaxis did not significantly influence the rate of VTE, but was associated with a significant increase in hematoma requiring a return to the operating room (relative risk=7.37, p=.048).

CONCLUSIONS

Pharmacologic prophylaxis, primarily with unfractionated heparin, after elective spine surgery was not associated with a significant reduction in VTE. However, there was a significant increase in postoperative hematoma requiring reoperation among patients undergoing prophylaxis. This raises questions about the routine use of unfractionated heparin for VTE prophylaxis and supports the need for further consideration of risks and benefits of chemoprophylaxis after elective spine surgery.

Clinically Significant Thromboembolic Disease in Adult Spinal Deformity Surgery: Incidence and Risk Factors in 737 Patients

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Describe the rate and risk factors for venous thromboembolic events (VTEs; defined as deep venous thrombosis [DVT] and/or pulmonary embolism [PE]) in adult spinal deformity (ASD) surgery.

METHODS

ASD patients with VTE were identified in a prospective, multicenter database. Complications, revision, and mortality rate were examined. Patient demographics, operative details, and radiographic and clinical outcomes were compared with a non-VTE group. Multivariate binary regression model was used to identify predictors of VTE.

RESULTS

A total of 737 patients were identified, 32 (4.3%) had VTE (DVT = 14; PE = 18). At baseline, VTE patients were less likely to be employed in jobs requiring physical labor (59.4% vs 79.7%, P < .01) and more likely to have osteoporosis (29% vs 15.1%, P = .037) and liver disease (6.5% vs 1.4%, P = .027). Patients with VTE had a larger preoperative sagittal vertical axis (SVA; 93 mm vs 55 mm, P < .01) and underwent larger SVA corrections. VTE was associated with a combined anterior/posterior approach (45% vs 25%, P = .028). VTE patients had a longer hospital stay (10 vs 7 days, P < .05) and higher mortality rate (6.3% vs 0.7%, P < .01). Multivariate analysis demonstrated osteoporosis, lack of physical labor, and increased SVA correction were independent predictors of VTE (r² = .11, area under the curve = 0.74, P < .05).

CONCLUSIONS

The incidence of VTE in ASD is 4.3% with a DVT rate of 1.9% and PE rate of 2.4%. Osteoporosis, lack of physical labor, and increased SVA correction were independent predictors of VTE. Patients with VTE had a higher mortality rate compared with non-VTE patients.

Inaccuracies in ICD Coding for Obesity Would Be Expected to Bias Administrative Database Spine Studies Toward Overestimating the Impact of Obesity on Perioperative Adverse Outcomes

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To determine if International Classification of Diseases (ICD) coding for obesity is biased toward certain subgroups and how potential bias may influence the outcomes of database research in spine.

SUMMARY OF BACKGROUND DATA

There has been increased use of national databases using administrative data in the spine surgery literature. Past research demonstrates that sensitivity of ICD codes for obesity is poor, but it is unknown if such inaccuracies are systematically biased and if they may bias studies utilizing such data.

METHODS

Patients who underwent elective posterior lumbar fusion, 2013 to 2016, at a large academic hospital were identified. All ICD codes assigned to the encounter were obtained. Body mass index (BMI) was calculated based on height and weight. The sensitivity of ICD coding for obesity was calculated. Sensitivity was compared for subgroups defined by demographic, comorbidity, intraoperative, and postoperative factors. The association of obesity (as defined by BMI≥30 and ICD coding) with 30-day postoperative adverse events was tested with multivariate regression.

RESULTS

The study included 796 patients. The overall sensitivity of ICD coding for obesity was 42.5%. The sensitivity of ICD coding for obesity was significantly higher in patients with greater BMI, diabetes, American Society of Anesthesiologists class≥III, increased length of stay, venous thromboembolism, any adverse event, and major adverse event. Multivariate analysis for determining outcomes of increased risk with obesity as defined by ICD coding included venous thromboembolism, major adverse events, and any adverse events. However, multivariate analysis for determining outcomes of increased risk with obesity defined by BMI did not yield any positive associations.

CONCLUSION

ICD codes for obesity are more commonly assigned to patients with other comorbidities or postoperative complications. Further, use of such nonrandomly assigned ICD codes for obesity has the potential to skew studies to suggest greater associated adverse events than calculated BMI would demonstrate.

LEVEL OF EVIDENCE

3.

Incidence and Risk Factors for 30-Day Unplanned Readmissions After Elective Posterior Lumbar Fusion

STUDY DESIGN

Retrospective study of prospectively collected data.

OBJECTIVE

To perform a multiinstitutional assessment on the incidence and risk factors for unplanned readmissions following elective posterior lumbar fusion (PLF) surgery.

SUMMARY OF BACKGROUND DATA

Understanding what may drive rehospitalizations is a necessary step toward higher quality care. Identifying risk factors for unplanned readmission is especially important for elective PLF, which is a common procedure that is known to be associated with significant adverse events.

METHODS

Adult patients undergoing PLF were identified using current procedure terminology (CPT) from the American College of Surgeons National Surgical Quality Improvement Program. Both descriptive and comparative statistics were performed for patient characteristics, clinical factors, and postoperative complications. Subsequently, a step-wise multivariate logistic regression was employed.

RESULTS

Of the 2301 patients who met inclusion criteria for this study, 117 were unplanned readmissions (5.1%). These occurred at a mean of 15.9 days (range: 3-30 days) after surgery. The risk-adjusted analysis revealed that bleeding disorder (odds ratio, OR = 2.8, confidence intervals, CI = 1.0-7.6, P = 0.043), insulin dependent diabetes (OR = 2.5, CI = 1.4-4.4, P = 0.004), and total length of stay > 5 days (OR = 1.8, CI = 1.2-2.8, P = 0.009) were independent predictors for unplanned readmission. Significant postoperative complications included wound complications (OR = 27.6, CI = 13.9-54.8, P < 0.0001), pulmonary embolism and/or deep vein thrombosis/thrombophlebitis (OR = 11.9, CI = 5.0-28.5, P < 0.0001), sepsis (OR = 8.5, CI = 2.3-32.1, P = 0.002), and urinary tract infections (OR = 2.4, CI = 0.9-6.9, P = 0.094).

CONCLUSION

The unplanned readmission rate for patients undergoing PLF was low, but this study's findings of potentially modifiable risk factors suggest that substantial improvement with this quality metric is possible.

LEVEL OF EVIDENCE

N/A.

The timing of venous thromboembolic events after spine surgery: a single-center experience with 6869 consecutive patients

OBJECTIVE

Venous thromboembolic events (VTEs), including both deep venous thrombosis (DVT) and pulmonary embolism, are a major cause of morbidity and mortality after spine surgery. Prophylactic anticoagulation, or chemoprophylaxis, can prevent VTE. However, the timing of VTEs after spine surgery and the effect of chemoprophylaxis on VTE timing remain underinvestigated.

METHODS

The records of 6869 consecutive spine surgeries were retrospectively examined. Data on patient demographics, surgical variables, hospital course, and timing of VTEs were collected. Patients who received chemoprophylaxis were compared with those who did not. Appropriate regression models were used to examine selection for chemoprophylaxis and the timing of VTEs.

RESULTS

Age (OR 1.037, 95% CI 1.023–1.051; p < 0.001), longer surgery (OR 1.003, 95% CI 1.002–1.004; p < 0.001), history of DVT (OR 1.697, 95% CI 1.038–2.776; p = 0.035), and fusion surgery (OR 1.917, 95% CI 1.356–2.709; p < 0.001) predicted selection for chemoprophylaxis. Chemoprophylaxis patients experienced more VTEs (3.62% vs 2.03% of patients, respectively; p < 0.001), and also required longer hospital stays (5.0 days vs 1.0 days; HR 0.5107; p < 0.0001) and had a greater time to the occurrence of VTE (median 6.8 days vs 3.6 days; HR 0.6847; p = 0.0003). The cumulative incidence of VTEs correlated with the postoperative day in both groups (Spearman r = 0.9746, 95% CI 0.9457–0.9883, and p < 0.0001 for the chemoprophylaxis group; Spearman r = 0.9061, 95% CI 0.8065–0.9557, and p < 0.0001 for the nonchemoprophylaxis group), and the cumulative incidence of VTEs was higher in the nonchemoprophylaxis group throughout the 30-day postoperative period. Cumulative VTE incidence and postoperative day were linearly correlated in the first 2 postoperative weeks (R = 0.9396 and p < 0.0001 for the chemoprophylaxis group; R = 0.8190 and p = 0.0003 for the nonchemoprophylaxis group) and the remainder of the 30-day postoperative period (R = 0.9535 and p < 0.0001 for the chemoprophylaxis group; R = 0.6562 and p = 0.0058 for the nonchemoprophylaxis group), but the linear relationships differ between these 2 postoperative periods (p < 0.0001 for both groups).

CONCLUSIONS

Anticoagulation reduces the cumulative incidence of VTE after spine surgery. The cumulative incidence of VTEs rises linearly in the first 2 postoperative weeks and then plateaus. Surgeons should consider early initiation of chemoprophylaxis for patients undergoing spine surgery.

Predictors of Readmissions and Reoperations Related to Venous Thromboembolic Events After Spine Surgery: A Single-Institution Experience with 6869 Patients

BACKGROUND

Readmission and reoperation are used as hospital and surgeon quality metrics. Venous thromboembolic (VTE) events, including deep vein thrombosis and pulmonary embolism (PE), are a major cause of readmission, morbidity, and mortality after spine surgery. Specific procedural, perioperative, and patient characteristics may be associated with these outcomes.

METHODS

We retrospectively examined records from 6869 consecutive spine surgeries at our institution. We collected data on patient demographics, surgery, hospital course, and 30-day rates of VTE, readmission, reoperation, and epidural hematoma. Stepwise multivariable logistic regression was used to identify independent predictors of each outcome.

RESULTS

Factors associated with VTE within 30 days of surgery include a history of VTE (odds ratio [OR] 3.92 [confidence interval 1.83-8.36], P < 0.001), estimated blood loss (EBL; OR 1.017 [1.005-1.029], P = 0.004), fracture (OR 5.42 [2.09-14.05], P = 0.001), history of PE (OR 4.04 [1.22-13.42], P = 0.023), and transfusion (OR 2.26 [1.07-4.77], P = 0.033). Factors associated with readmission were a history of PE (OR 3.27 [1.07-9.97], P = 0.038), PE (OR 8.07 [2.26-28.8], P = 0.001), transfusion (OR 2.54 [1.55-4.17], P < 0.001), comorbid disease burden (OR 1.35 [1.01-1.80], P = 0.041), and tumor surgery (OR 2.84 [1.32-6.10], P = 0.007). Factors associated with reoperation were EBL (OR 1.024 [1.006-1.042], P = 0.008), transfusion (OR 3.86 [1.38-10.79], P = 0.01), and PE (OR 6.05 [1.03-35.62], P = 0.046). Transfusion was associated with epidural hematoma within 30 days (OR 7.38 [1.37-39.83], P = 0.02).

CONCLUSIONS

Transfusion and EBL are associated with numerous negative outcomes. Transfusion is an independent predictor of VTE, readmission, reoperation, and epidural hematoma requiring evacuation. Specific pathologies were associated with specific negative outcomes.

Impact of Inpatient Venous Thromboembolism Continues After Discharge: Retrospective Propensity Scored Analysis in a Longitudinal Database

STUDY DESIGN

Propensity score matched retrospective study using a nationwide longitudinal database.

OBJECTIVE

To quantify the longitudinal economic impact of venous thromboembolism (VTE) complications in spinal fusion patients.

SUMMARY OF BACKGROUND DATA

VTE is a rare and serious complication that may occur after spine surgery. The long-term socioeconomic impact understanding of these events has been limited by small sample sizes and a lack of longitudinal follow-up. We provide a comparative economic outcomes analysis of these complications.

METHODS

We identified 204,308 patients undergoing spinal fusion procedures in a national billing claims database (MarketScan) between 2006 and 2010. Cohorts were balanced using 50:1 propensity score matching and outcome measures compared at 6, 12, and 18 months postoperation.

RESULTS

A total of 1196 (0.6%) patients developed postoperative VTE, predominantly occurring following lumbar fusion (69.7%). Postoperative VTE patients demonstrated an increase in hospital length of stay (7.8 vs. 3.3 d, P<0.001) and a decreased likelihood of being discharged home (71% vs. 85%, P<0.001). A $26,306 increase in total hospital payments (P<0.001) was observed, with a disproportionate increase seen in hospital payments ($22,103, P<0.001), relative to physician payments ($1766, P=0.001).At 6, 12, and 18 months postfusion, increased rates of readmission and follow-up clinic visits were observed. Delayed readmissions were associated with decreased length of stay (3.6 vs. 4.6 d, P<0.001), but increased total payments, averaging at $21,270 per readmission. VTE patients generated greater cumulative outpatient service payments, costing $8075, $11,134, and $13,202 more at 6, 12, and 18 months (P<0.001).

CONCLUSIONS

VTEs are associated with longer hospitalizations, a decreased likelihood of being discharged home, and overall increases of hospital resource utilization and cost in inpatient and outpatient settings. VTE patients generate greater charges in the outpatient setting and are more likely to become readmitted at 6, 12, and 18 months after surgery, demonstrating a significant socioeconomic impact long after occurrence.

LEVEL OF EVIDENCE

Level III-therapeutic.

Body mass index as a predictor of outcome in total knee replace: A systemic review and meta-analysis

BACKGROUND

To conduct a meta-analysis with randomized controlled trials (RCTs) published in full text to demonstrate database to show the associations of perioperative, postoperative outcomes of normal and high body mass index (BMI) to provide the predictive diagnosis for clinic.

METHODS

Literature search was performed in PubMed, Embase, Web of Science and Cochrane Library for information from the earliest date of data collection to February. RCTs comparing the benefits and risks of normal BMI with those of high BMI in primary total knee arthroplasty (TKA) were included. Statistical heterogeneity was quantitatively evaluated by X2 test with the significance set P<0.10 or I2>50%.

RESULTS

Seven RCTs consisting of 33,778 patients were included. (6065 normal BMI patient; 27,713 high BMI). The results showed that high BMI was related to a greater increase in operative time, post-operative range of motion (ROM), post-operative Knee Society and function scores (KSS), infection rate (P<0.1). No differences in pulmonary embolism and perioperative mortality rates were found between normal and high body mass index patients with follow-up≥5years (P>0.1).

CONCLUSIONS

Compared with normal BMI patients, high BMI patients demonstrated an increased risk of perioperative and postoperative complications and clear difference about complications between normal and high BMI about TKA.

Thrombotic and Infectious Morbidity Are Associated with Transfusion in Posterior Spine Fusion

BACKGROUND

Although previous investigators have established an association between blood transfusion and adverse outcomes, the relative frequency of different morbid events and the association with transfusion dose are not well understood.

QUESTIONS/PURPOSES

The purpose of the study is to characterize the relationship between blood transfusion and different types of morbidity after posterior spine fusion.

METHODS

We retrospectively analyzed electronic medical records for 963 patients who underwent posterior spinal fusion surgery at a single institution, of which 603 (62.6%) received an allogeneic blood transfusion. Then, we assessed patient and surgical characteristics in a risk-adjusted fashion to identify various morbid event rates and independent predictors in these adverse outcomes.

RESULTS

Compared to the non-transfused patients, transfused patients had a higher incidence of any morbid event (9.1 vs. 2.5%. P < 0.0001), thrombotic events (4.6 vs. 1.1%, P = 0.0025), and hospital-acquired infections (2.3 vs. 0.6%, P = 0.039). Renal, respiratory, and ischemic morbidity occurred less frequently and were not more common in transfused patients. Risk-adjusted analysis revealed a dose-response effect, whereby for each unit of allogeneic blood transfused, the risks of any morbid event (OR 1.183; 95% CI 1.103-1.274; P < 0.0001), thrombotic complication (OR 1.104; 95% CI 1.032-1.194; P = 0.0035), and infectious complication (OR 1.182; 95% CI 1.077-1.332; P = 0.0002) were increased.

CONCLUSION

Our data demonstrate risk-adjusted and transfusion dose-related increases in perioperative morbidity, with thrombotic and infectious events being the most common.

Adipose tissue location and contribution to postinjury hypercoagulability

OBJECTIVES

Obesity is associated with a hypercoagulable state at baseline and following injury. The anatomic location of adipose deposition may influence the type of thrombotic event, with visceral adipose tissue (VAT) associated with arterial thrombosis and subcutaneous adipose tissue (SAT) predisposing to venous thrombosis. We sought to determine whether adipose tissue amount and location correlated with measures of coagulation.

METHODS

All adult Level I trauma activations at our institution between January 2013 and August 2014 who underwent admission abdominal computed tomography scan and had admission rotational thromboelastometry measurements were included. Patients were excluded for history of anticoagulant use and known coagulopathy/hypercoagulable state. Admission computed tomography was used to obtain cross-sectional VAT and SAT areas at the umbilicus utilizing a novel software system; VAT and SAT measurements were associated with markers of coagulation utilizing Spearman correlation and stepwise linear regression with significance set at p < 0.05.

RESULTS

Two hundred forty-two patients met inclusion and exclusion criteria. Sixty-nine percent of patients sustained blunt injury, 79% were male, mean age was 40 years, 25% were obese or morbidly obese, and mean Injury Severity Scale score was 17. Seventeen percent of patients had acute deep venous thrombosis or pulmonary embolism during hospitalization. Neither SAT nor VAT correlated with prothrombin time, international normalized ratio, or partial thromboplastin time. Subcutaneous adipose tissue correlated positively with platelet count. Visceral adipose tissue and SAT correlated negatively with clot formation time and positively with TEM fibrinogen, α angle, maximum clot firmness, and lysis at 30 minutes; stronger correlations and greater significance were seen between SAT and these measures except for lysis at 30 minutes. Stepwise linear regression confirmed significant relationships between SAT and clot formation time, AA, and maximum clot firmness; VAT showed a significant relationship with TEM fibrinogen.

CONCLUSIONS

Increased adipose tissue correlates with relative hypercoagulability following trauma. Subcutaneous adipose tissue shows a stronger relationship with functional measures of coagulation, suggesting that SAT may be associated with hemorrhage resistance and hypercoagulability after injury.

LEVEL OF EVIDENCE

Prognostic study, level IV.

Coagulation Profile as a Risk Factor for 30-Day Morbidity and Mortality Following Posterior Lumbar Fusion

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

The aim of this study was to identify associations between abnormal coagulation profile and postoperative morbidity and mortality in patients undergoing posterior lumbar fusion (PLF).

SUMMARY OF BACKGROUND DATA

The literature suggests that abnormal coagulation profile is associated with postoperative complications, notably the need for blood transfusion. However, there is little research that directly addresses the influence of coagulation profile on postoperative complications following PLF.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program database (ACS-NSQIP) was utilized to identify patients undergoing PLF between 2006 and 2013. Nine thousand two hundred ninety-five patients met inclusion criteria. Multivariate analysis was utilized to identify associations between abnormal coagulation profile and postoperative complications.

RESULTS

Low platelet count was an independent risk factor for organ space surgical site infections (SSIs) [odds ratio (OR) = 6.0, P < 0.001], ventilation >48 hours (OR = 4.5, P = 0.002), Acute renal failure (OR = 5.8, P = 0.007), transfusion (OR = 1.6, P < 0.001), sepsis (OR = 2.2, P = 0.037), reoperation (OR = 2.5, P = 0.001), and death (OR = 3.7, P = 0.049). High partial thromboplastin time (PTT) was an independent risk factor for ventilation >48 hours (OR = 5.6, P = 0.002), cerebrovascular accident (CVA)/stroke with neurological deficit (OR = 5.1, P = 0.011), cardiac arrest (OR = 5.4, P = 0.030), transfusion (OR = 1.5, P = 0.020), and death (OR = 4.5, P = 0.050). High International Normalized Ration (INR) was an independent risk factor for pneumonia (OR = 8.7, P = 0.001), pulmonary embolism (OR = 5.6, P = 0.021), deep venous thrombosis/Thrombophlebitis (OR = 4.8, P = 0.011), septic shock (OR = 8.4, P = 0.048), and death (OR = 9.8, P = 0.034). Bleeding disorder was an independent risk factor for organ space SSI (OR = 5.4, P = 0.01), pneumonia (OR = 3.0, P = 0.023), and sepsis (OR = 4.4, P < 0.001).

CONCLUSION

Abnormal coagulation profile was an independent predictor of morbidity and mortality in patients undergoing PLF. As such, it should be considered in preoperative optimization and risk stratification.

Association between insurance status and patient safety in the lumbar spine fusion population

BACKGROUND CONTEXT

Lumbar fusion is a common and costly procedure in the United States. Reimbursement for surgical procedures is increasingly tied to care quality and patient safety as part of value-based reimbursement programs. The incidence of adverse quality events among lumbar fusion patients is unknown using the definition of care quality (patient safety indicators [PSI]) used by the Centers for Medicare and Medicaid Services (CMS). The association between insurance status and the incidence of PSI is similarly unknown in lumbar fusion patients.

PURPOSE

This study sought to determine the incidence of PSI in patients undergoing inpatient lumbar fusion and to quantify the association between primary payer status and PSI in this population.

STUDY DESIGN

A retrospective cohort study was carried out.

PATIENT SAMPLE

The sample comprised all adult patients aged 18 years and older who were included in the Nationwide Inpatient Sample (NIS) that underwent lumbar fusion from 1998 to 2011.

OUTCOME MEASURE

The incidence of one or more PSI, a validated and widely used metric of inpatient health-care quality and patient safety, was the primary outcome variable.

METHODS

The NIS data were examined for all cases of inpatient lumbar fusion from 1998 to 2011. The incidence of adverse patient safety events (PSI) was determined using publicly available lists of the International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis codes. Logistic regression models were used to determine the association between primary payer status (Medicaid and self-pay relative to private insurance) and the incidence of PSI.

RESULTS

A total of 539,172 adult lumbar fusion procedures were recorded in the NIS from 1998 to 2011. Patients were excluded from the secondary analysis if "other" or "missing" was listed for primary insurance status. The national incidence of PSI was calculated to be 2,445 per 100,000 patient years of observation, or approximately 2.5%. In a secondary analysis, after adjusting for patient demographics and hospital characteristics, Medicaid and self-pay patients had significantly greater odds of experiencing one or more PSI during the inpatient episode relative to privately insured patients (odds ratio 1.16, 95% confidence interval 1.07-1.27).

CONCLUSIONS

Among patients undergoing inpatient lumbar fusion, insurance status is associated with the adverse health-care quality events used to determine hospital reimbursement by the CMS. The source of this disparity must be studied to improve the quality of care delivered to vulnerable patient populations.

The Effect of Coagulopathies on Perioperative Complications and Clinical Outcomes in Patients Treated With Posterior Lumbar Fusions

STUDY DESIGN

A retrospective database review.

OBJECTIVE

The aim of this study was to compare complication rates following one to two-level lumbar spine surgery in patients with primary hypercoagulable states and coagulopathies.

SUMMARY OF BACKGROUND DATA

Both hypercoagulable states and coagulopathies are not uncommon conditions that have the potential to significantly alter perioperative patient management. However, there are few studies that document the added risk of medical complications following spine surgery in these patient populations.

METHODS

The PearlDiver database (2005-2012) was utilized to determine perioperative complication rates in patients with primary hypercoagulable states and coagulopathies who underwent primary one to two-level posterolateral lumbar spine fusion. Control cohorts without specific hematologic disorders were matched by demographics and comorbidities. Ninety-day complication rates were determined, along with revision rates at one and two years. When considering complication rate comparisons between matched cohorts, P < 0.005 was considered significant.

RESULTS

In total, 746 patients with coagulopathies and 2753 patients with primary hypercoagulable states were selected. Matched control cohorts contained 74,879 and 54,007 patients, respectively. Hypercoagulable patients had significantly increased rates of medical complications [odds ratio (OR) 1.4], infections (OR 1.6), and venous thromboembolisms (OR 9.0) during the three months following spine surgery and same-day transfusions (OR 1.2) when compared with matched controls (P < 0.001). Patients with von Willebrand disease or hemophilia had increased rates of three-month infections (OR 2.3) and transfusion (OR 2.0) when compared with a matched control group (P < 0.005). One- and two-year revisions rates were not significantly higher for either pathologic cohort when compared to matched controls.

CONCLUSION

Both primary hypercoagulable states and coagulopathies increase infection and transfusion rates following one to two-level lumbar spine surgery.

LEVEL OF EVIDENCE

3.

Influence of Obesity on Access-Related Complications During Anterior Lumbar Spine Interbody Fusion

OBJECTIVE

The anterior lumbar spine approach has gained in popularity in recent years, but the associated access-related complications for obese patients have not been clearly established. This study aimed to analyze the relationship between obesity or overweight and the safety of the anterior lumbar spine approach.

METHODS

Eighty-four consecutive patients admitted for lumbar spine surgery by anterior approach between 2011 and 2014 were included. The surgical approach consisted of left lateral minilaparotomy and retroperitoneal dissection. The patients were categorized into 3 different groups according to their body mass index (BMI). The studied outcomes measures included medical history, BMI, the number of fused levels, surgery duration, blood loss, vascular injury, day of discharge, surgical revision, and wound infection.

RESULTS

No significant difference was found across the BMI groups with regard to vascular or infectious complications. The duration of surgery was significantly higher in the obese group.

CONCLUSIONS

Because BMI does not seem to increase the overall risk of complications, the anterior lumbar spine approach should be considered in obese or overweight patients, as in nonoverweight patients.

Prophylactic inferior vena cava filter placement prior to lumbar surgery in morbidly obese patients: Two-case study and literature review

Background:

Preoperative “prophylactic” placement of inferior vena cava (IVC) filters in morbidly obese patients (e.g., body mass index [BMI] >40 or BMI over 35 with hypertension/diabetes) undergoing multilevel decompressive lumbar laminectomies may reduce the risk of postoperative pulmonary embolism (PE), and death.

Methods:

Two patients, ages 69 and 68, with morbid obesity (BMI's of 40.4 and 37.5 both with hypertension and diabetes), received prophylactic IVC filters prior to L1–S1 laminectomies. Intraoperatively and postoperatively, both received alternating compression stocking prophylaxis, and received subcutaneous heparin 5000 U q12 h 48 h after surgery until discharge; none developed deep venous thrombosis (DVT) or PE, and both filters were uneventfully removed within 3 postoperative months.

Results:

The spinal surgical literature largely supports the placement of IVC filters for major risk factors; obesity (BMI >40), a history of DVT/PE, cancer, fusions, hypercoagulation syndromes, pulmonary/circulatory disorders, preoperative/postoperative immobility, staged procedures (five spinal levels), combined anterior-posterior surgery, iliocaval manipulation, age >80, and prolonged surgery (e.g., >261 min vs. >8 h). Although the safety and efficacy of prophylactic IVC filters for spine surgery in patients with morbidly obesity are well substantiated, those for bariatric patients are less clear.

Conclusions:

Prophylactic IVC filters were successfully placed/retrieved in 2 morbidly obese patients, ages 68 and 69, undergoing L1–S1 lumbar decompressions. Although the spine surgery literature documents the safety/efficacy of prophylactic IVC filters in patients with morbid obesity, the bariatric literature still has major concerns.